I would be willing to bet the write off is accounting 'magic' or an attempt to derail the investigation. The private equity almost always get their pound of flesh and leave the 'surviving' company they spin out drowning in debt.
Their normal MO is buy low, sell anything of value and slash expenditures by closing facilities they can't liquidate quickly while collecting huge 'management fees' to extract capital. With the 'new and improved' balance sheet, the company borrows money to make their 'investor' whole and finally have a new IPO or sell to a lower class of private equity vampires.
Research the destruction of Simmons, the largest bedding company in the US. This is the case study for how a series of 7 private equity deals decimated a company.
30 years hard labor for all Blackstone Group, KKR & Co., Bain Capital Partners, Carlyle Group excecutives and their lawyers at once. They are the leaders behind the demise of the USA and the manufacturing industry here.
I am no lawyer but I understand that a non-compete deal or cartel formation is considered illegal under U.S. antitrust law.
But it does remain the case that the private equity companies' bad timing for investing in 2006 and writing off in 2009 is probably their best defense, and may get them off the hook.
The case against would argue that the various leveraged buy deals were worth more than the amount paid IN 2006 and that the PE companies would have paid more but for the alleged collusion.
In other words the case against would argue that the PE companies are guilty AND incompetent.